首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3716篇
  免费   276篇
  国内免费   3篇
耳鼻咽喉   40篇
儿科学   96篇
妇产科学   40篇
基础医学   471篇
口腔科学   38篇
临床医学   371篇
内科学   914篇
皮肤病学   177篇
神经病学   414篇
特种医学   135篇
外科学   480篇
综合类   17篇
一般理论   1篇
预防医学   257篇
眼科学   76篇
药学   249篇
中国医学   10篇
肿瘤学   209篇
  2024年   8篇
  2023年   27篇
  2022年   38篇
  2021年   124篇
  2020年   96篇
  2019年   123篇
  2018年   120篇
  2017年   88篇
  2016年   100篇
  2015年   109篇
  2014年   146篇
  2013年   214篇
  2012年   287篇
  2011年   276篇
  2010年   148篇
  2009年   126篇
  2008年   207篇
  2007年   211篇
  2006年   221篇
  2005年   209篇
  2004年   182篇
  2003年   158篇
  2002年   136篇
  2001年   53篇
  2000年   38篇
  1999年   34篇
  1998年   23篇
  1997年   28篇
  1996年   36篇
  1995年   31篇
  1994年   25篇
  1993年   17篇
  1992年   30篇
  1991年   35篇
  1990年   24篇
  1989年   25篇
  1988年   22篇
  1987年   29篇
  1986年   19篇
  1985年   16篇
  1984年   16篇
  1983年   16篇
  1982年   22篇
  1981年   14篇
  1980年   8篇
  1977年   7篇
  1976年   7篇
  1975年   8篇
  1974年   8篇
  1966年   6篇
排序方式: 共有3995条查询结果,搜索用时 15 毫秒
1.
2.
3.
The clinical presentation of electrical injury commonly involves physical, cognitive, and emotional complaints. Neuropsychological studies, including case reports, have indicated that electrical injury (EI) survivors may experience a broad range of impaired neuropsychological functions, although this has not been clarified through controlled investigation. In this study, we describe the neuropsychological test findings in a series of 29 EI patients carefully screened and matched to a group of 29 demographically similar healthy electricians. Participants were matched by their estimated premorbid intellectual ability. Multivariate analysis of variance was used to assess group differences in the following neuropsychological domains: attention and mental speed, working memory, verbal memory, visual memory, and motor skills. EI patients performed significantly worse on composite measures of attention/mental speed and motor skills, which could not be explained by demographic differences, injury parameters, litigation status, or mood disturbance. Results suggest that cognitive changes do occur in patients suffering from electrical injury.  相似文献   
4.
OBJECTIVE: Analysis of the effects of a comprehensive focal spasticity program in adult patients. DESIGN: Retrospective study of an out-patient cohort. PATIENTS: One hundred patients were enrolled in the study (54 men and 46 women, mean age 41 years (SD 14). Cerebral palsy and stroke were equally common (80% in total). The remaining patients had miscellaneous diagnoses, including traumatic brain injury. METHODS: On average 230 units (SD 101) of botulinum toxin A Botox was given for 227 principal therapy targets chosen by the patient or the caregiver. One patient could have several targets for therapy. Administration of botulinum toxin was combined with 260 additional therapeutic interventions, most of which were forms of physical therapy. The effects were assessed after 6 weeks and compared with baseline functional abilities 1-2 weeks prior to therapy. RESULTS: Improvement was observed for 211 (93%) therapy targets, no change in 15 (7%), and impairment in 1, corresponding to an overall improvement in 90 patients (90%), 9 unchanged (9%) and worsening in 1. Spasticity assessment (Ashworth scale 0-4; 30 patients) showed a statistically significant improvement (median at baseline was 3 vs 2 after therapy, mean difference 1.2, p<0.001). CONCLUSION: Improvement was observed in >or=90% of patients and in their principal therapeutic targets in a cohort receiving their first focal spasticity treatment with botulinum toxin A and additional therapy. A strict strategy for patient selection and comprehensive management was followed.  相似文献   
5.
The generation of thrombin-like activity from rat, human, bovine and mouse prothrombin by Echis carinatus venom (ECV) treatment was compared using a partially purified system (i.e. whole ECV and isolated prothrombin). A rapid increase in coagulant activity was obtained within 0.5 to 2 min., being constant upon further incubation for 60 min. A large variation in coagulant activity of the ECV generated thrombin from the four species was found, whereas no differences were found for the amidolytic activities. The coagulant activities of the ECV generated thrombin was also low compared with the corresponding thrombin activities obtained by physiological activation. Coagulant activity of the ECV generated thrombin levelled off at increasing concentration of prothrombin in the sample as measured by the one-stage coagulation assay. By measuring amidolytic activity a linear relationship to the concentration of prothrombin was found, however. These findings indicate that ECV converts prothrombin from the four different species to a thrombin-like protein with properties distinct from -thrombin. The lack of linearity in the ECV generated clot activity with increasing concentration of prothrombin could be explained by assuming a dimerization of the thrombin like protein molecules making them less accessible to fibrinogen. The significance of these observations for the quantification of prothrombin from different species is discussed.  相似文献   
6.
The Eating Disorder Inventory, Version 2 (EDI‐2) is a questionnaire used clinically and in research all over the world. EDI‐2 is cross‐culturally valid, yet normative values may depend on culture. Norms and reliability of the Danish version have to date been lacking, and will be presented in this article, comparing patients (N = 575) and controls (N = 881). Also, internal reliability of scales is tested for both groups. Differences between norms of the Danish and the North American version of EDI were small but significant for all scales except asceticism (eating disorder patients) and ineffectiveness, interpersonal distrust and maturity fears (normal controls). For both groups the internal consistency was >0.70 for all subscales except asceticism. Although differences across the eating disorder diagnostic groups were dubious, the EDI‐2 is useful to screen for eating problems in the general population as well as to rate progress and outcome among eating disorder patients. Copyright © 2009 John Wiley & Sons, Ltd and Eating Disorders Association.  相似文献   
7.
8.
Protein synthesis in skeletal muscle is known to decrease during contractions but the underlying regulatory mechanisms are unknown. Here, the effect of exercise on skeletal muscle eukaryotic elongation factor 2 (eEF2) phosphorylation, a key component in protein translation machinery, was examined. Eight healthy men exercised on a cycle ergometer at a workload eliciting ∼67% peak pulmonary oxygen consumption     with skeletal muscle biopsies taken from the vastus lateralis muscle at rest as well as after 1, 10, 30, 60 and 90 min of exercise. In response to exercise, there was a rapid (i.e. < 1 min) 5- to 7-fold increase in eEF2 phosphorylation at Thr56 that was sustained for 90 min of continuous exercise. The in vitro activity of skeletal muscle eEF2 kinase was not altered by exercise indicating that the increased activity of eEF2 kinase to eEF2 is not mediated by covalent mechanisms. In support of this, the increase in AMPK activity was temporally unrelated to eEF2 phosphorylation. However, skeletal muscle eEF2 kinase was potently activated by Ca2+–calmodulin in vitro , suggesting that the higher eEF2 phosphorylation in working skeletal muscle is mediated by allosteric activation of eEF2 kinase by Ca2+ signalling via calmodulin. Given that eEF2 phosphorylation inhibits eEF2 activity and mRNA translation, these findings suggest that the inhibition of protein synthesis in contracting skeletal muscle is due to the Ca2+-induced stimulation of eEF2 kinase.  相似文献   
9.
Abstract: Polycythaemia vera (PV) is a myeloproliferative disorder characterized by haematopoietic progenitor cells being hypersensitive to cytokines such as erythropoietin, interleukin-3, stem cell factor and insulin-like growth factor 1, which results in an increased production of mature blood cells. The pathogenetic cellular mechanism(s) behind this hypersensitivity to cytokines is unknown, but the number of cytokine receptors and the interaction between ligand and receptor are normal in PV. Interest has therefore focused on post-receptor mechanism(s). Haematopoietic cell phosphatase (HCP) is an intracellular tyrosine phosphatase that has been demonstrated to regulate proliferative signals negatively induced by the cytokines mentioned above. Moreover, motheaten mice that genetically lack HCP have an increased amount of erythroid progenitors that are hypersensitive to Epo, and patients with familial polycythaemia have been shown to exhibit a mutation of the Epo receptor gene that includes the docking site for HCP. We therefore studied mRNA expression of HCP in pure populations of CD34+ cells, granulocytes, platelets and lymphocytes from patients with PV, chronic myeloid leukaemia (CML) or essential thrombocythemia (ET), as well as healthy controls. Using a polymerase chain reaction analysis employing specific primers for HCP, we failed to detect any abnormalities of HCP expression in PV in any of the cell populations that were examined. Moreover, HCP mRNA expression was similar in ET and CML compared to controls. Finally, Western blot analysis revealed a normal HCP protein content in PV granulocytes and platelets. We therefore conclude that neither an impaired expression of the HCP gene nor a defect in HCP protein synthesis is present in PV, and does not seem to play a role in the aetiology of this disorder.  相似文献   
10.
A car-borne NaI(Tl) spectrometric system was used together with a 137Cs source to obtain realistic data in the search for unshielded and semi-shielded orphan sources. The potassium-stripped counts (PSC) method was used to estimate the influence by the shielding on the detection ability. A reduction of about 5% in the critical distance was obtained for the semi-shielded source. A curve fitting method was also developed and evaluated. Results from the curve fitting method showed inferior ability to find the source compared to the PSC method. However, it can be a useful complementary tool, for characterisation of the source shielding, and estimation of the distance from the road.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号